Walk in.
Made friends with one of the employees. After coming in for a while shopping for home theater products engaged in a conversation about how awesome radioshack was and in turn was asked if I wanted to work there. After careful consideration a said yes and asked what I needed to do. I was told to apply on Indeed in addition to the radioshack website because the manager received those applications directly. Also, be sure to know the store number for the location in which you wish to apply for.
The next day I had the employee/friend unofficially introduce me to the manager and mentioned that I was interested in working there.
I was followed up by receiving a phone call the next day and went in for a formal interview the day after that.
Before the week was over, I had a job offer. =)